Usage of tests is a popular way of gaining information about learner's knowledge, and test generation systems provide a possible method of facilitation of test process. There are diferent approaches to such systems, and one of them suggests the usage of special representations of knowledge and describing the systems as knowledge handlers or the whole test process as ontology-based. In this work a possible way of representing a test generation system as an ontology is described. Methods of the handling such structure are described with a focus on question selection and test score. The proposed approach use generic ontological characteristics, therefore it is domain independent. It provides a great variability of test variants and knowledge reuse between test cases.